Apparatus for visual detection of suspended matter in fluid



June 22, 1954 w. T. FLEMING 2,681,590

APPARATUS FOR VISUAL DETECTION OF SUSPENDED MATTER IN FLUID Filed Dec.27, 1950 INVENTOR A WILL/AM I Fl HIM 6 ATTORNEY Patented June 22, 1954APPARATUS FOR VISUAL DETECTION OF SUSPENDED MATTER IN FLUID William T.Fleming, West Orange, N. J., assignor to Specialties DevelopmentCorporation, Belleville, N. J., a corporation of New Jersey ApplicationDecember 27, 1950, Serial No. 202,977

6 Claims. 1

. The present invention relates to apparatus for visually detectingsuspended matter in fluid, and, more particularly, to improvements insmoke detectors primarily adapted for use on aircraft or other craft orvehicles where the space for such apparatus on the instrument panel isextremely limited.

Heretofore, visual smoke detectors have been utilized to supervise oneor several compartments .or zones in which smoke may occur bycontinuously withdrawing samples of the air from such zones orcompartments and passing a stream of air withdrawn through a beam oflight to illuminate smoke particles suspended in the stream whereby thepresence of smoke may be observed visually in the stream. In connectionwith such smoke detectors, it has been found that the illuminatedparticles can be seen more readily when looking in the direction towardthe light source but obliquely thereto.

tector wherein stray light which might hinder the observer is reduced toa minimum.

Another object is to provide such a smoke detector wherein provision ismade for readily determining whether or not the beam of light forilluminating the air stream is being directed through the stream.

A further object is to provide means for selectively rendering the lightbeam determining means just mentioned effective and ineffective.

Other and further objects of the inventionwill be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice. In accordance with the present invention,the

foregoing objects are generally accomplished by providing apparatuscomprising in combination a casing having a sight opening including awindow, a light source for providing a beam of light, means fordirecting the beam in the general direction of the opening but along oneside of the window whereby the beam will be viewed obliquely through thewindow when looking therethrough, and means for conducting a stream offluid into the light beam.

, In a preferred embodiment. of the invention 'tially flush with thepanel.

about to be described, the air stream and the light beam are directedthrough a common aperture in a partition positioned within the casing,a. shield is positioned between the window and this partition, but toone side of the light beam, and translucent means adapted to beilluminated by the beam are positioned adjacent the window directly inthe path of the beam. The translucent means serves as a pilot lightadapted to indicate whether or not the light source is functioning. Thepilot light may be rendered effective and ineffective at will by ashutter disposed between these means and the light source, which shutteris operable from the exterior of the casing. The air, in which smoke isto be detected, preferably, is introduced into the casing between thepartition and the end wall of the casing having the window therein, andis Withdrawn from the casing at the opposite end thereof.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawing,forming a part of the specification, wherein:

Figure 1 is a front elevational view of a smoke detecting device inaccordance with the invention.

Figure 2 is a sectional view taken along the line 2-2 on Figure 1,illustrating the interior of the device.

Figure 3 is a fragmentary sectional view taken along the line 3-3 onFigure 2, illustrating the shutter for controlling the pilot light.

Referring to the drawing in detail, there is shown a smoke detectingdevice generally com- "prising a casing I U, a. light source forproviding a beam of light, such as a lamp II, and conduit means forpassing an air stream through the light beam.

The casing It is generally rectangular, and has a front wall I2, a rearwall IS, a top wall III, a bottom wall I5, and side walls it. Thesewalls may be so dimensioned to provide a casing which is small andcompact to facilitate mounting the same on an instrument or controlpanel of a craft or vehicle with the front wall l2 being substan- Inpractice, it has been found feasible to utilize a casing which occupiesless than thirty cubic inches of space.

The front wall I2 has a rectangular sight opening IT in the upperportion thereof, a transparent window 53 extending inwardly into thecasing from the lower edge of the opening and a translucent button ordisc I9 just below the opening, the purposeof which will be madeapparent hereinafter.

A partition 20 is positioned in the casing between the front and rearwalls thereof which preferably extends from the top to the bottom wallsand from one side wall to the other, whereby the casing is divided intoforward and rearward zones. The partition, as shown, has a lowervertical section 2i on which the lamp H is mounted atthe side withintherearward casing zone, and has an upper, downwardly and rearwardlyinclined section 22 formed with an aperture 23 which is in horizontalalignment with the opening IT.

The conduit means for circulating anair stream through the casing inwhich smoke is to be detected comprise a tube 24 extending through therear wall i3 and the partition 2!} to the forward casing zone, and anopeningin the rear wall hav ing a tube 25 in communication therewith.Preferably, the air is introduced through the tube 2/! into the forwardzone, is passed through the aperture 23 in partition 22 to the rearwardzone, and'is removed from the rearward zone through the'tube 25. h V

Theai'r stream in being so circulated passes through a beam of lightadapted to illuminate smoke particles suspended in the stream. Thislight beam is provided by the lamp H and is directed through thepartition aperture 23 by a reflector '26 mounted on the top wall it inthe rearward zone. The reflector is so positioned that the light beam isdirected substantially directly towards the opening I 'l but just belowthe lower side edge thereof whereby the center of the beam is directedon the center of the button i9. In'this manner, the light beam and airstream intersect each other, and the button is illuminated to ,the othersidewall of the casing. Thesebafiles depend from the top wall .of thecasing-and are inclined downwardly and rearwardly substantially at thesame angle as the partitionwhereby they are 'parallel'thereto. Thebafiie 23 nearest the opening is longer than the baffie 29 and its loweredge is nearer to the center of thebeam" than that of the baffle 29. Bybeing so arranged,

the shorter bafiie 28 blocks the light diffused ,upwardly at a wideangle and the longer baffie '28' blocks the stray light of the upperpart of the beam which gets past the shorter bafile.

As shown herein, the inner edge of the window T8 is supported bysuitable means adjacent the lower edge of the bailie 28, and ispositioned substantially parallel to the light beam to minimize thereflection of stray light thereon from the interior of the casing. Theforward end of the top wall 14 shields the window against reflection ofstray light at the exterior of the casing.

When the interior of the casing is observed by looking through openingll and the window 18, as indicated by the arrow A (Figure 2), the bafile28 obscures the aperture 23. The line of vision thusis in generaldirection towards the origin of the beam but is oblique thereto wherebyany illuminatedsmoke particles can be readily seen.

. sible.

This is accomplished with an extremely small and compact device byarranging the apertured partition, the bafiles, the opening and thewindow as shown.

While the provision of a pilot light is a desirable feature, it is alsodesirable that the instrument panel, particularly near thesmokedetecting observation window, be kept as dark as pos- Hence, it iscontemplated that the pilot light should be visible only when it isdesired to determine whether or not the lamp is in workmg order, andshould be darkened at all other times. This is accomplished in aconvenient manner by placing a movable shutter between the light beamand the button [9.

As shown in Figures 2 and 3, a shutter 30 in the form'of a segment of acircular disc is mounted on and is secured to a shaft 3| which isrotatably supported in a bushing 32 and extends outwardly through thefront wall of the casing. The shutter has a slot 34 at one side thereofwhich permits the light beam to pass therethrou'gh' and be directed onthe translucent button. The other or to the'left to block the beam anddarken the button. A handle 39 is provided on the --shaft3l at theexterior of the casing for effecting .movement of the shutter, andcooperating indicia are provided on the front wall of the casing(Figure 1) to indicate the on and off pilot light positions 7 of'theshutter.

From the foregoing description, it will be seen that the presentinvention provides a simple, practical and economical visual smokedetecting device which is small and compact and lends itself for use incraft or vehicles where space is at a premium. The device is reliableinper .formance, and cannot get out of order during normal usagethereof, except for failure of the lamp which would be detected by thepilot light arrangement.

As various changes may be made in the form,

construction and arrangement of the parts hereinywithout departingfrom'the spirit and scope of the invention and without sacrificingany-of its advantages, it is to be understood tha-twall matter herein isto be interpreted as illustrative and not in any limiting sense.

I claim: V 1. In apparatus for detecting suspended-mat- .ter in a'fluid,the combination of a casing :hav-

ing an upper wall and having a front wall adapted to constitute aportion of an instrument panel and being provided'with a sight opening,said casing having a window extending from about the lower edge of saidopening inwardly into said-casing in a generally longitudinal directionwith respect to said casing, a light source in said casing for providinga beam of light, means for directing the light beam towards the innerside of said front wall in a direction substantially parallel tosaidwindow, opaque bafli'e m'eansfin said casing in the line'-of."visionbetween, said opening and said light beam "directing means,

and means for circulating a stream of fluid in which suspended matter isto be detected through said casing and through the light beam adjacentsaid window.

2. In apparatus for detecting suspended matter in a fluid, thecombination of a casing having an upper wall and having a front walladapted to constitute a portion of an instrument panel and beingprovided with a sight opening, said casing having a window extendingfrom about the lower edge of said opening inwardly into said casing in agenerally longitudinal direction with respect to said casing and havingan opaque baffle wall extending from said window adjacent its inner endto said upper wall, a light source in said casing rearwardly disposed ofsaid bafile wall for providing a beam of light, means for directing thelight beam towards the inner side of said front wall in a directionsubstantially parallel to said window, and means for circulating astream of fluid in which suspended matter is to be detected through saidcasing and through the light beam adjacent said window.

3. In apparatus for detecting suspended matter in a fluid, thecombination of a casing having an upper wall and having a front walladapted to constitute a portion of an instrument panel and beingprovided with a sight opening, said casing having a window extendingfrom about the lower edge of said opening inwardly into said casing in agenerally longitudinal direction with respect to said casing and havingan opaque bafiie wall extending from said window adjacent its inner endto said upper wall, a partition in said casing having an aperturetherein, a light source in said casing rearwardly disposed of saidpartition for providing a beam of light, means between said light sourceand said partition for directing the light beam through said partitionaperture towards the inner side of said front wall in a directionsubstantially parallel to said window, and means for circulating astream of fluid in which suspended matter is to be detected through saidcasing and through the light beam adjacent said window.

4. In apparatus for detecting suspended matter in a fluid, thecombination of a casing having a rear wall an upper wall and having afront wall adapted to constitute a portion of an instrument panel andbeing provided with a sight opening, said casing having a windowextending from about the lower edge of said opening inwardly into saidcasing in a generally longitudinal direction with respect to said casingand having an opaque bafiie wall extending from said window adjacent itsinner end to said upper wall, a partition in said casing having anaperture therein, a light source in said casing rearwardly disposed ofsaid partition for providing a beam of light, means between said lightsource and said partition for directing the light beam through saidpartition aperture towards the inner side of said front wall in adirection substantially parallel to said window, and means forcirculating a stream of fluid in which suspended matter is to bedetected through said casing and through the light beam adjacent saidwindow, said last mentioned means including an inlet and an outlet insaid rear wall and including a conduit in said casing connected to saidinlet, and having an opening between said front wall and said partition.

5. In apparatus for detecting suspended matter in a fluid. thecombination of a casing having a front wall provided with a sightopening, said casing having a window extending from about the lower edgeof said opening inwardly into said casing in a generally longitudinaldirection with respect to said casing, translucent means in said walladjacently below said window, means for circulating a stream of fluid inwhich suspended matter is to be detected through said casing and througha zone adjacently below said window, a light source in said casingproviding a beam of light, means for directing the beam of light substantially parallel to said window and through said zone and directly onsaid translucent means, a shutter in said casing adapted to bepositioned between said translucent means and said light beam directedon said translucent means, and means for operating said shutter from theexterior of said front wall.

6. In apparatus for detecting suspended matter in a fluid, thecombination of a casing having an upper wall and having a front walladapted to constitute a portion of an instrument panel and beingprovided with a sight opening, said casing having a window extendingfrom about the lower edge of said opening inwardly into said casing in agenerally longitudinal direction with respect to said casing,translucent means in said wall adjacently below said window, a lightsource in said casing for providing a beam of light, means for directingthe light beam towards the inner side of said front wall in a directionsubstantially parallel to said window and directly on sai translucentmeans, opaque bafile means in said casing in the line of vision betweensaid opening and said light beam directing means, and means forcirculating a stream of fluid in which suspended matter is to bedetected through said casing and through the light beam adjacent saidwindow.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,012,230 Grant Aug. 20, 1935 2,283,769 Schwanzel May 19, 19422,356,238 Gillett et a1 Aug. 22, 1944 2,485,588 Grant Oct. 25, 1949

